This invention relates to connector apparatus for connecting a flat ribbon cable to a printed circuit board or other like circuit device, and in particular multiple edge connector strip apparatus adapted to clamp a ribbon cable to a printed circuit board.
Flexible flat ribbon cables are being increasingly used at present in electronics because of their easy applicability and their reduced space requirement. The connection of such cables with other electronic units, especially printed circuit boards, has been provided to date by soldering, crimping, pressing or similar means, or via specific plug-in connections. These processes and devices usually serve their purpose satisfactorily, but are often expensive and usually not reliable enough. There is an inherent difficulty in making a reliable connection, specifically in the case of the plug-in connections, due to the flexibility of the flat ribbon cable.
A device for the detachable connection of a flexible flat ribbon cable with a printed circuit board is already known from West German Pat. No. 19 20 988. This patent discloses a wedge-shaped clamping means around which a flexible flat ribbon cable with strip conductors non-isolated from the outside is laid, and is fastened by a clamping frame. The strip conductors of the printed circuit board are spanned by a plastic clamping saddle which is inserted with its ends into matching openings of the printed circuit board by means of a snap-in connection. The clamping means with the flexible flat ribbon cable is pushed into the opening between the clamping saddle and the printed circuit board and pressed far enough to achieve force fit, and the strip conductors of the flat ribbon cable contact the congruent strip conductors or contact surfaces of the printed circuit board. This detachable connection can be arranged either at the edge or on the inner surface of the printed circuit board, but is not attachable around an edge of the printed circuit board.
Another connector is described in European Pat. No. 0,006,725, which serves the purpose of providing an electrical connection between the strip condutors of a flexible flat ribbon cable and those of a printed circuit board. To achieve this there is provided a clamp-like metal holder which has laterally projecting tabs which are bent over after being introduced into openings in the printed circuit board. Even though the cable is detachable, the holder cannot be removed often from the printed circuit board because the tabs break off upon repeated bending in alternate directions. The contact pressure is brought about by a plurality of flexible tongues which press the opposite strip conductors against one another. Since the flexible tongues are cut out as one piece together with the metal holder, the flexible flat ribbon cable or any strip conductors or contact surfaces on the side on which the flexible tongues lie, must be isolated to avoid short circuit.
Another similar connector assembly is described in European patent application No. 0,026,568. The clamp-like holder, being very long, has several projecting tabs spaced over its length for holding onto the printed circuit board. This is necessary to achieve as uniform a contact pressure as possible for all of the flexible tongues. There is also a lifting device which makes it possible to eliminate or reduce the contact pressure by lifting the flexible tongues, so that the flexible flat ribbon cable can first be laid into the holder without applying force, and can be pressed only thereafter by using the device.